1. Field of the Invention
The invention is directed to an accelerator pedal module for controlling the power to a motor or engine, and more particularly to such an accelerator pedal having a two-point calibration.
2. Description of the Prior Art
For controlling the power of a driving machine of a motor vehicle, the demands of the motor vehicle driver are transmitted to the driving machine from a pedal lever, disposed within range of the motor vehicle driver, by means of electric lines and via a controller. To that end, a sensor is provided that measures the position of the pedal lever. Measured values from the sensor, after suitable processing, are transmitted to the driving machine by the controller. A kick-down mechanism and an electric switch are often provided as well.
The sensor of the accelerator pedal module is intended, at a certain position of the pedal lever, to furnish an electrical signal at a precisely predetermined level. To that end, the sensor is adapted in a certain position of the pedal lever. In the accelerator pedal module shown in International Patent Disclosure WO97/12781 and in German Patent Disclosure DE 195 36 606 A1, this is done by rotating the sensor housing, in a certain position of the pedal lever, far enough that the electrical signal output by the sensor is located within a predetermined, narrow tolerance band. Upon an actuation of the pedal lever, the electrical signal output by the sensor then changes, so that the controller can detect the position of the pedal lever at that time.
Upon an actuation of the pedal lever between the position of repose of the pedal lever and the end position of the pedal lever, there is a so-called kick-down angle position, in which the restoring force exerted on the pedal lever rises abruptly. The kick-down angle position is located shortly before the end position of the pedal lever. An electric switch is provided on the accelerator pedal module. The electric switch typically serves to switch over a gear of the motor vehicle. The electric switch is switched over by the pedal lever whenever the pedal lever is located between the kick-down angle position and the end position.
Because the slope of the electrical signal output by the sensor is unavoidably affected by tolerances as a function of the angle position of the pedal lever, and because the switching point of the electric switch is also not entirely free of tolerance, and since furthermore the mechanism of the accelerator pedal module has tolerances with regard to the attainable angle positions, the switching path between the kick-down angle position and the angle position at which the electric switch switches over, must be relatively long, in the known accelerator pedal module. The kick-down switching path between the kick-down angle position and the end position of the pedal lever is also fairly long in the known accelerator pedal module, for the tolerance reasons given. Another disadvantage is that because of tolerances, the fact that the electrical signal of the sensor upon reaching the kick-down angle position is relatively widely scattered must be accepted into the bargain.
As a result, the paths for actuating the pedal lever must be kept relatively long overall, and the scattering of the electrical signal of the sensor in the kick-down angle position must be taken into account by suitable design of the electric controller, for instance by means of a suitable control unit.
The accelerator pedal module embodied according to the invention has the advantage over the prior art that, largely independently of production-dictated tolerances in the electrical signal of the sensor, a very precise electrical signal of the sensor can be attained that is dependent on the particular position of the pedal lever at the time. In particular, it can be attained that in both the position of repose of the pedal lever and the kick-down angle position of the pedal lever, the electrical signal of the sensor is within very close tolerances. A further advantage is that the switching path between the kick-down angle position and the switchover of the electric switch can be kept desirably quite short, and the pivot angle between the kick-down angle position of the pedal lever and the end position of the pedal lever can also be kept fairly short. As a result, the advantage is obtained that the driver operating the pedal lever has the feeling of precise control of the power of the driving machine between the position of repose of the pedal lever and the kick-down angle position of the pedal lever, and the switching path and the pivot angle between the kick-down angle position and the end position of the pedal lever can be kept fairly short. A long switching path and a long pivot angle between the kick-down angle position and the end position would in fact be perceived as a fairly unpleasant idle travel by the driver. Since only short idle travel distances for the pedal lever overall are required, the advantage is obtained that the accelerator pedal module can be made relatively small in size overall, and that the available installation space in the passenger compartment for actuating the pedal lever is fairly small.